Amid general handwringing over the IRA's return to violence, you'll hear not a word from one group of Irish people. There are millions of them, but they haven't been on television discussing Friday's mortar attack on an army barracks. No one would even have thought to ask their opinions.

The Irish in Britain are politically invisible. They have tried to stay out of the Troubles: it was not they who blew people up: the bombers came almost exclusively from the Republic and Northern Ireland. And since the ceasefire, they - unlike Irish-Americans - have played a minimal role in shaping the peace. When outrages occur, John Hume, Ian Paisley, Sir Patrick Mayhew and John Bruton all make their predictable comments. But not this community in our midst that knows so much, feels so much and says so little. Like the Arabs in Israel proper, they are in every town; but they remain loyally, dutifully silent.

It isn't difficult to understand such diffidence. They have not always felt welcome. The witty Irish gentleman has long been acceptable in the drawing room, but his countrymen have often been less well-regarded.

The Duke of Wellington famously summed up English disdain when asked: "Sir, is it true you were born in Ireland?" The Iron Duke replied: "Being born in a stable doesn't make you a horse."

Popular images of the Irish man have portrayed him as a foolish, idle figure of fun. One Victorian contributor to Punch described him as "a creature manifestly between the Gorilla and the Negro." This community, which has seen Catholicism in Britain fully tolerated only since the 1830s and Irishness usually regarded as suspect, is reluctant to generate controversy.

The tide of hostility and the several miscarriages of justice that followed Birmingham and Guildford pub bombings in 1974 served as a reminder to keep heads down. Twenty-five years of conflict in Northern Ireland did little to challenge perceptions of the Irish as irrational and violent: Ian Paisley's performance only compounded the problem by making Ulster Protestants additionally subject to prejudices against which Catholics alone had previously laboured.

But in this British community, whose size the census does not even measure (the best guess is 1 million Irish-born, 8 million of Irish descent), something extraordinary is happening. A remarkable surge in cultural self-confidence is taking place. We are seeing nothing short of the greening of England, as the Irish in Britain set aside a traditional low profile, moving out of the ghetto, beyond enclaves of clubs and pubs and into the mainstream.

A swift pint in O'Shea's hints at the transformation. 'The Rocky Road To Dublin' is belting out at a fierce pace. Behind the bar, the Irish Post, Longford Leader and Sligo Champion are on sale, there's a Powers Whiskey mirror, hurling sticks displayed on the wall and the drink is flowing. Denis Keegan, Guinness in hand, is waxing on about how proud he is to be Irish. It all sounds like a typical, rough, Irish pub, hidden away in some deprived quarter of an English city, frequented by sad, downtrodden, reluctant exiles, given to nostalgia for the ould sod.

But O'Shea's is no back street shebeen: it's in the centre of Manchester and one of the city's fashionable watering holes. The pub is a short walk from the Arndale Centre, which the IRA all but demolished a fortnight ago. A few years ago, such a pub would probably not have existed. If it did, the publican would have boarded it up for fear of a backlash.

But old attitudes have been transformed. Manchester has not taken its anger out on the Irish community. Perhaps this is understandable: 20 per cent of the population has Irish roots. Many of the emergency workers interviewed after the bomb had Irish accents: the man trapped in a tower for three days was named Danny O'Neill.

But an important reason may be a huge change in perceptions. Suddenly, Irishness is hip. "Irish culture is seductive. It has become a signifier for hedonism with soul," says Frank Cottrell-Boyce, a former scriptwriter for Coronation Street. "There was a decisive moment during the World Cup, when Ireland was there and England wasn't, when people came out as Irish who hadn't been before. Irishness could represent them on the world stage." And a fashion for the craic is surviving even the IRA's latest campaign.

O'Shea's is just one of 60 Irish theme bars opened in the Manchester area in the past couple of years. (One - Paddy's Rat and Carrot - was a bomb casualty.) In March, the city held its first annual Irish festival week, complete with a St Patrick's Day parade past the town hall. More than a thousand people currently play Gaelic football in the area. Planning permission has been granted for a huge, 13-acre centre celebrating Gaelic culture. Yet fresh migration from Ireland virtually dried up years ago: Manchester's vibrancy is built around a young generation that has no brogue.

In London, Irish restaurants, such as Mulligans in Mayfair, are fashionable. The Royal Court in the West End is devoted to celtic drama. Riverdance, U2, repeated Irish victories in the Eurovision song contest, the success of the Republic's football team and international popularity of the Irish president, Mary Robinson, have all made Irishness flavour of the moment. Extensive Radio 4 coverage of Hibernian arts, be it poetry, music or theatre suggests an ascendant culture. At a low-brow level, so many English stag parties now go off to Dublin for the weekend that the Irish government wants to stem the flow.

The sources of this new confidence are many. There was the arrival in the Eighties of a new immigrant wave, a third of them graduates, coming from a country where European Union membership has fostered a sense of modernity.

Some, particularly the unskilled, have had problems. Shane McGowan (late of the Pogues) sings of the recession-hit building worker: "I'm buggered to damnation/And I haven't got a penny/To wander the dark streets of London." But many of the "Ryanair generation" have lived well, flitting back and forth on cheap airfares, using Britain as a staging post before heading on to Europe and the United States. No longer are the Irish the poor relations.

The second generation, those born of the Fifties' immigrants, is particularly important. Better educated than their parents, they know how Britain works. They sound, in their desire to forge a special identity, like confident young British Muslims. Just as Muslims have tapped into an international culture, while dropping their parents' yearning for a return to the homeland, so this second generation is at home here while still choosing to be Irish. It is, after all, this generation that has supplied the key players for the successful Irish Republic team. Stars such as Liverpool-born Jason McAteer and Aston Villa's Cockney midfielder Andy Townsend would have vied for an England place, had they not decided it was cooler to be Irish. Two decades ago, it would have been unthinkable for them to spurn the flag of St George.

Back in O'Shea's, Denis Keegan is one of many Mancunians whose parents were born in Ireland. Sounding as English as Bobby Charlton, his traditional Claddagh ring, trademark of the young, is the only outward sign of his origins.

"It seems to be OK to be Irish," says Keegan, 30, a graduate, whose father was a labourer. "It used to be that the only place you could go was to old men's clubs down Stockport Road. But now there are so many places and your English friends come too. It's really in your face.

"My Dad came here 40 years ago and he worked his bollocks off. There were signs that no blacks or Irish need apply - my parents went through all the prejudice. But the second generation doesn't kow-tow. A lot of people are more up-front than their parents. I was the first in my family to go to university.We have to stand up for ourselves and hold on to our culture."

Sean McGuire, 29, Manchester-born manager in a ceiling tiles company, thinks people are just beginning to let their Irishness become visible. He plays the flute, tin whistle, does Irish dancing and plays Irish sports.He seems, like some Irish-Americans, more Irish than the Irish themselves.

Melanie Conway, 27, a travel agent, is typical. "I used to say I was English. I would not say my parents were Irish, but now I say that I'm of Irish descent."

Jim Bryan, 36, a Manchester electrician, has even more tenuous links with Ireland: his father left Co. Galway as a baby nearly 70 years ago and has never returned. "I went back for the first time last year, met the relations. I loved it. Nice and slow, not like rushing at 80 miles an hour here in Manchester. We're keeping in touch now - exchanging Christmas cards. There's a bit of Irish in me, I think. When you come back, you realise you understand yourself a little bit better."

This tendency for the second and third generation to continue to feel Irish confounds many sociologists. The Irish were expected to assimilate quickly. This has, after all, apparently happened in the oldest Victorian, Irish settlement, on Merseyside. Few in Liverpool would now call themselves Irish. However, most give themselves a local identity - Liverpudlian or Scouse - rather than the usual national one. And all the characteristics of Liverpudlianism - verbalness, Catholicism, high value placed on family, irreverence for the Protestant work ethic - are vestiges of their rural, pre-industrial ancestors. Liverpudlianism seems, in short, a mask for Irishness.

The newer Irish communities used a single mask: Catholicism. They attended Catholic schools, where, according to Mary Hickman's authoritative new study of the Irish in Britain*, they learned to define themselves as Catholic rather than as Irish. Their public rituals - confession and catechism on Saturday, Mass on Sundays, a miniature wedding dress at seven for the girls' First Communion - distinguished them denominationally but not ethnically.

Now, as the power of the Catholic Church wanes and Irishness becomes less of a social impediment, this community appears to be seeking a more secular expression of difference. They are more self-aware: there are now popular degree courses in Irish Studies. Indeed, some university courses are over-subscribed, with many non-Irish students trying to gain a place. There is a campaign for the 2001 census to produce an accurate figure of how many Irish people live in Britain.

It is also worth knowing what they think about Northern Ireland. "No one agrees with violence or people getting hurt," says Sean McGuire. "People are keen on a united Ireland, but what happens over there does not directly impinge on us. There is no urgency to stand up and be counted. Peace is all that people want.

"In Britain, Irish people discuss Northern Ireland among themselves, but it's such a touchy subject, that it would take someone with an awful lot of balls to tell the people of Britain what they should do. People would be afraid that if they started talking about politics, they would be accused of being IRA sympathisers.

"As the peace process got going, people started to talk more freely. I think now they will go back into their shells."

There is, however, no sign that the revival in Irish culture will wane. "This is not an anti-British thing," says McGuire. "It's Irish blood running through the veins. Something to be proud of, not to be forgotten."